HomeMy WebLinkAboutMS 05-11; CAZADERO HOMES; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2004-06-29CHRISTIAN WHEELER ECETVE. ENGINEERJNG
ENGINEERING
REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
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PROPOSED RESIDENCES
.2817 AND 2819 CAZADERO DRIVE
CARLSBAD, CALIFORNIA
SUBMITTED TO:
CAZADERO HOMES, INC.
2954 HAWKS EYE PLACE
CARLSBAD, CALFIORNIA 92009
SUBMITTED BY:
CHRISTIAN WHEELER ENGINEERING
4925 MERCURY STREET
SAN DIEGO, CALIFORNIA 92111
4925 Mercury Street + San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758
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June 29, 2004
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. Cazadero Homes, Inc.
I . 2954 Hawks Eye Place
Carlsbad, California 92009
CHRiSTIAN WHEELER
ENGINEERING
CWE 204060Z1
Attention: Mr. Ron Paul
SUBJECT: REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION,
PROPOSED RESIDENCES, 2817-2819 CAZADERO DRIVE,
CARLSBAD, CALIFORNIA.
Dear Mr. Paul:
In accordance with your request, we have completed a preliminary geotechnical investigation for the subject
property. We are presenting herewith our findings and recommendations.
No geotechnical conditions were found that would preclude the construction of the proposed residential project
provided the recommendations presented in this report are followed. Based on our investigation, we have
found that the site is underlain, by artificial fills and slopewash underlain by Cretaceous-age Santiago Peak
Volcanics. The Santiago Peak Volcanics encountered in our investigation are generally medium dense to dense
and suitable. to support the proposed construction. The existing artificial fill material appears to have been
properly compacted and properly benchedinto competent. formational material and is, therefore, considered
suitable in its present condition to support settlement-sensitive improvements; however, the upper portions will
need to be scarified, moisture conditioned, and recompacted. The existing slopewash material is considered
unsuitable in its present condition to support settlement-sensitive improvements. As such, the slopewash will
need to be removed and be replaced as properly compacted fill material. This being accomplished, the
proposed residences can be supported by conventional spread foundations and with conventional concrete
slabs-on-grade.
No geologic hazards of sufficient magnitude to preclude development of the site as we presently contemplate it
are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable from a
4925 Mercury Street' + San Diego, CA 92111 + 8.58-496.9760 + FAX 858-496-9758
C\VE 2040602.1 June 24, 2004 Page No. 2
:1 geologic perspective for the. proposed construction, provided the structure is designed in accordance with the
requirements of the most recent edition of the Uniform Building Code and the local governmental agencies.
If you' have any questions after reviewing this report, please do not hesitate to contact our office. This
opportunity to be of professional service is sincerely appreciated.
Respectfully submitted,•
CHRISTIAN WHEELER ENGINEERING
Charles H. Christian, R.G.E. #00215 Curti B.. Burdett, C.E.G. #1090
O CHC:CR.B:scc:shv
cc: (6) Submitted
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TABLE OF CONTENTS
PAGE
Introduction and Project Description...............................................................................................................................1
ProjectScope ................................................................................... ........ ... .... ........ ............................................................. -2
Findings................................................................................................................................................................................. 3
SiteDescription...............................................................................................................................................................3
General Geology and Substirface Conditions............................................................................................................3
GeologicSetting and Soil Description ............................................................................... . ..................................... 3
ArtificialFill ......................................... . .................................................................................................................. 4
Slopewash......................................................................................................................................... . ...................... .4
Weathered Undifferentiated Santiago Peak Volcanics........................................................................................4
Groundwater......................................................
....................................................................... . .................................... 4
TectonicSetting..........................................................................................................................................................5
GeologicHazards............................................................................................................................................................
GroundShaking ........................................................................................................................................................... 5
SurfaceRupture .......................................................................................................................................................... 6
Landslide Potential and Slope Stability......................................................................................................................6
Liquefaction......... ........................................................................................................................................................6
Flooding.......................................................................................................................................................... .............. 6
Tsunamis......................................................................................................................................................................6
Seches.................................. . ......................................................................................................................................... 6
Conclusions............................................................................................................................................................ .............. 7
Recommendations................................................................................................................................................. .............. 7
Grading and Earthwork.................................................................................................................................................7
General........................................................................................................................................................... ............... 7
Observationof Grading ............................................................................................................................... .............. 7
Clearing and Grubbing ................................................................................................................................. .............. 8
SitePreparation ............................................................................................................................................... .............. 8
Building Pad Undercuts ............................................ - .................................................................................. .............. 8
Processing of Fill Areas............................................8
Compaction and Method of Filling..........................................................................................................................8
Cut and Fill Slope Construction .................................................................................... . ............................ .............. 9
Surface Drainage' ........................................................................................................................................... .............. 9
TemporaryCut Slopes.............................................................................................................................................10
SlopeStability ..................................................................................................................................................... ............ 10
General........................................................................................................................................................... ............ 10
ErosionControl. ............................................................................................................................................ ............ 10
Foundations....................................................................................................................................................... ............ 11
General........................................................................................................................................ ............................... 11
Foundation Dimensions ................................................................................................................................. . ............... 11
BearingCapacity .... . ........................................................................................................................................ ............ 11
FootingReinforcement............................................................................................................................................11
Lateral Load Resistance ................................................................................................................................. ............ 11
SettlementCharacteristics.......................................................................................................................................11
Foundation Plan Review ............................................................................................................................... ............ 12
Foundation Excavation Observation .....................................................................................................................12
SeismicDesign Parameters ......................................................................................................................... ............ 12
On-Grade Slabs ................................................................................................................................................. ............ 13
General........................................................................................................................................................... ............ 13
CWE 2040602.1
Proposed Residences
Cazadero Drive, Carlsbad, California
Interior Floor Slabs . 13
Moisture Protection for Interior Slabs .13
ExteriorConcrete Flatwork .......................................................... . ...................................................................... ...13
EarthRetaining Walls ............................................................... ............................................... ........................................ 14
PassivePressure .................................................. ......................................................................................................14
EquivalentFluid Pressure ........ . ................................................................................................................................ 14
Surcharge.................................................................................................................................................................... 14
Waterproofingand Subdrain Observation ............................................................................................................ 14
Backfill........................................................................................................................................................................ 14
Limitations.......................................................................................................................................................................... 14
Review, Observation and Testing ........................................................................................................................... ..... 14
............................................ ....................................................... . ............. Uniformity of Conditions ............................. 15
Change in Scope ............................................................................................................................... . ............................ is
TimeLimitations ..............................................................................................................................................
... ........... 15
ProfessionalStandard ................. . ...................................................
................................................................................ 15
Clients Responsibility......................................................................................................................................16
FieldExplorations .................................................................................................................................................. ........... 16
Laboratory. Testing ........................................................................ . ............................................................................ . ....... 17
ATTACHMENTS
TABLES
Table I Maximum Ground Acceleration, Page 5
Table II Seismic Design Parameters, Page 12
FIGURES
Figure 1 Site Vicinity Map, Follows Page 1
PLATES
Plate I Site Plan
Plates 2-7 Test Trench Logs
Plate 8 Suggested Retaining Wall Subdrain Detail
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APPENDICES
Appendix A References
Appendix B Recommended Grading Specifications - General Provisions
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CWE 2040602.1
Proposed Residences
Cazadero Drive, Carlsbad, California
/
CHRISTIAN WHEELER
ENGINEERING
PRELIMINARY GEOTECHNICAL INVESTIGATION
PROPOSED RESIDENCES
2817-2819 CAZADERODRIVE
CARLSBAD, CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of a preliminary geotechthcal investigation performed for the proposed
residences to be constructed on a previously graded lot located at 2817 and 2819 Cazadero Drive, in the La
Costa area of Carlsbad, California. Figure Number 1 presented on the following page provides a vicinity map
showing the'location of the property.
The subject site is a vacant parcel of land located at 2817 and 2819 Cazadero Drive and is identified as
Assessor's Parcel Number 215-320-45. The lot has been graded into arelatively level pad that is about six feet
above Cazadero Drive. We understand that it is proposed to construct two, single-family residences on the lot
The proposed structure on the northwest portion of the site will be situated on the existing pad, two-stories in
height, and of wood-frame construction. The proposed structure on the southeast portion of the site will have
split levels wth two- and three-story portions, and will have a partially subterranean garage at the front with an
interior retaining wall. The above-grade portion of the structure will be of wood-frame construction while the
retaining portions are expected to consist of masonry block construction. Both sturcturès will be supported by
conventional shallow spread footings and the lower floors will have on-grade concrete floor slabs. Grading is
expected to consist of cuts of about 12 feet from the existing grades and fills of about 5 feet from the existing
grades.
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This report has been prepared for the exclusive use of Cazadero Homes, Inc. and their design consultants for
specific application to the project described herein. Should-the project be changed in any way, the modified
plans should be submitted to Christian Wheeler Engineering for review to determine their conformance with
our recommendations and to determine if any additional subsurface investigation, laboratory testing and/or
recommendations are necessary. Our professional services have been. performed, our findings obtained and our
- 4925 Mercury Street • San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758
CWE.2040602.1 June 29, 2004 Page No. 2
recommendations-prepared in accordance with generally accepted engineering principles and practices. This
warranty is in lieu of all other warranties, express or implied.
PROJECT SCOPE
Our preliminary geotechnical. investigation consisted of surface reconnaissance, subsurface exploration,
obtaining representative soil samples, laboratory testing, analysis of the field and laboratory data and review
of relevant geologic literature. Our scope of service, did not include assessment of hazardous substance
contamination, recommendations to prevent floor slab moisture intrusion or the formation of mold within
the structure, or any other services not specifically described in the scope of services presented below. More
specifically, the intent of this analysis was to:
Explore the subsurface conditions of the site to the depths influenced by the proposed
construction;
Evaluate, by laboratory tests and our experience, the engineering properties of the various strata
that may influence the proposed construction, including soil bearing capacities, expansive
characteristics and settlement potential;
Describe the general geology at the site including possible geologic hazards that could have an
effect on the site construction, and provide the seismic design parameters required by the most
recent edition of the Uniform Building Code;
ci) Address potential construction difficulties that may be encountered due to soil conditions,
groundwater, or geologic hazards, and provide recommendations concerning these conditions;
e) - Develop soil-engineering criteria for the site preparation and grading, and address the stability of
cut and fill slopes;
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f) Recommend an appropriate foundation system for the type of structure anticipated and develop
soil engineering design criteria for the recommended foundation design;
I g) Present our professional opinions this written report that includes, in addition to our findings and
recommendations, a site plan showing the location of our subsurface explorations and a summary
of our laboratory test results.
SITE VICINITY MAP
(Adapted from Thomas Brothers Maps)
PROPOSED RESIDENCES
2817-2819 CAZADERO DRIVE
CARLSBAD, CALIFORNIA
North
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( -, .'-/ •4
'
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C\VE 2040602.1 June 2004 Figure 1
CWE 2040602.1 June 29, 2004 Page No. 3
It is not 'within the scope of our services to perform laboratory tests to evaluate the chemical characteristics
of the on-site soils in regard to their potentially corrosive impact to on-grade concrete and below grade
improvements. If desired, we can submit representative soil, samples to a chemical laboratory for analysis.
We suggest that such samples be obtained after grading is complete and the soils that can affect concrete and
other improvements are in place. Further, it should be understood Christian Wheeler Engineering does not
practice corrosion engineering.. If such an analysis is necessary, we recommend that the developer retain an
engineering firm that specializes in this field to consult with them on this matter.
FINDINGS
SITE DESCRIPTION
The subject site is an irregular-shaped parcel of land located at 2817 and 2819 Cazadero Drive, in the La
Costa area of Carlsbad, California. The subject site is identified as Assessor's Parcel Number 215-320-45, and
as Lot 306 of La Costa Meadows Unit No. 2 (Map 6905). The lot is vacant and has been graded to have a
relatively level pad in the western portion. An unimproved driveway along the north side of the lot provides
access to the pad. There is an approximately 6-foot-high fill slope at the front of the lot and a 12- to 15-foot-
high cut slope at the rear of the lot, at the base of a high, gently ascending natural hillside. The lot is bounded
on the north and south by single-family residential properties. The lot has approximately 100 feet of frontage
along Cazadero Drive, ranges from approximately 215 to 225 feet in depth, and has a rear property line length
of about 36 feet. On-site elevations range from a low of approximately 245 feet (MSL) in the west corner,
the grade of Cazadero Drive, to a high of approximately 269 feet (MSL), in the southeast corner of the site.
A few piles of construction debris, gravel.and cobble were found on the building pad. The building pad area is
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relatively void of vegetation, while the upper, undisturbed portions of the site consist of relatively heavy
vegetation comprised of native brush.
GENERAL GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject property is located in the Foothills
Physiographic Province of San Diego County. Based upon the results of our limited exploration and analysis of
readily available, pertinent geologic and geotechnical literature, we have determined that the site is predominantly
underlain by Jurassic-Cretaceous-age, undifferentiated Santiago Peak Volcanics that are overlain by man-placed
ED materials in the western portion and natural slopewash materials in the eastern portion. The soils encountered
during our subsurface explorations are described below in order of increasing age:
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CWE 2040602.1 June 29, *2004 Page No. 4
ARTIFICIAL FILL (Qaf): A layer of artificial fill was encountered in four of our five subsurface
explorations, Trenches T-1 through T-4. The estimated limits of the existing fill are shown on the site
plan attached as Plate Number 1. In general, the existing fill material is limited to the western portion of
the graded pad and the adjacent fill slope; however, a relatively thin layer of fill was noted in the eastern
portion of the graded pad. Within Trench T-3, which was excavated at the western edge of the graded
pad, the fill layer was found to have a thickness ranging from 6 feet at. the west end of the trench to 2.5
feet at the east end. Within Trenches T-1, T-2, and T-4, the fill layer was only about six inches thick
The fill material was found toy consist of grayish- to medium-brown, silty-sand (SK that was
typically damp to moist Within Trench T-3, the material was medium dense to dense in consistency.
Within the Trench T-1, T-2, and T-4 the material was generally loose in consistency. Based on our
observation of the fill layer exposed within Trench T-3, it appears that the fill was properly compacted
and properly benched into competent formational material. As such, the existing artificial fill material is
considered suitable in its present condition to support settlement-sensitive improvements; however, the
upper portions will need to be scarified, moisture conditioned, and reconipacted in accordance 'with the
recommendations presented in the "Site Preparation" section of this report
SLOPEWASH (Qsw): Although not encountered within any of our exploratory trenches, this material
was visually observed in the existing cut slope within the eastern portion of the site. The slopewash
deposits consisted of medium to dark brown, silty sands M) that were damp to moist and loose to
medium dense in consistency. There appeared to be as much as four feet of the slopewash above the
undifferentiated Santiago Peak Volcanics within the cut slope, but localized thicker deposits May exist
WEATHERED UNDIFFERENTIATED SANTIAGO PEAK VOLCANICS (KJsp): As well as
p. being visually logged on a cut slope within the eastern portion of the site, Jurassic-Cretaceous-age
materials identified as the undifferentiated Santiago Peak Volcanics were encountered within each of our
test trenches. The material comprising the Santiago Peak Volcanics consisted of reddish-brown to gray,
sandy gravel (GP). The material was damp to moist and medium dense to dense in consistency. The
upper few feet of the formational material is moderately to highly fractured. These materials are
considered suitable in their present condition to support fill and/or settlement-sensitive improvements.
GROUNDWATER: No groundwater was encountered in our explorations and we do not anticipate any
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. significant groundwater related problems during or after construction provided that proper drainage is
maintained. However, it should be recognized that minor groundwater seepage conditions might occur after
development of a site even where none were present before development These are usually minor phenomena
and are often the result of an alteration in drainage patterns and/or an increase in irrigation water. Based on the
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C\VE 2040602.1 . June 29, 2004 Page No. .5
permeability characteristics of the soil and the anticipated usage and development, it is our opinion .that any
seepage conditions, should they develop,.will be minor in extent These potential "nuisance" conditions can.
- typically be mitigated by the use of proper landscaping techniques.
TECTONIC SETTING: No faults are known to traverse the subject site. However, it should be noted that
much of Southern California, including the San Diego County area, is characterized by a series of Quaternary-
age fault zones that consist of several individual, en echelon faults that generally strike in a northerly to
northwesterly direction. Some of these fault zones (and the individual faults within the zone) are classified as
"active" according to the criteria of the California Division of Mines and Geology. Active fault zones are
those that have shown conclusive evidence of faulting during the Holocene Epoch (the most recent 11,000
years).
A review of available geologic maps indicates that the active Rose Canyon Fault Zone is located
approximately 12 kilometers southwest of the subject site. Other active fault zones in the region that could
possibly affect the site include the Coronado Bank and San Clemente Fault Zones to the southwest and the
Elsinore, Earthquake Valley, San Jacinto, and San Andreas Fault Zones to the northeast
GEOLOGIC HAZARDS
S GROUND SHAKING: A likely geologic hazard to affect the site is ground shaking as a result of movement
along one of the major active fault zones mentioned above. The maximum ground accelerations that would be
attributed to a maximum magnitude earthquake occurring along the nearest fault segments of selected fault zones
that could affect the site are summarized in the following Table I..
TABLE I: MAXIMUM GROUND ACCELERATIONS
Fault Zone. Distance Maximum Magnitude
Earthquake
Maximum Ground
Acceleration
Rose Canyon 12 km 6.9 magnitude 0.18 g
Newport-Inglewood 18 km 6.9 magnitude 0.13 g
Coronado Bank 36 km 7.4 magnitude 0.10 g
Elsinore 37 km 7.1 magnitude 0.07 g
Earthquake Valley 62 km 6.5 magnitude 0.04 g
San Jacinto 74 km 7.2 magnitude 0.05 g
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CWE 2040602.1 June 29, 2004' Page No. 6
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Probable ground shaking levels it the site could range from slight to moderate, depending on such factors as •
the magnitude of the seismic event and the distance to the epicenter. It is likely that the site will experience
the effects of at least one moderate to large earthquake during the life of the proposed improvements.
SURFACE RUPTURE: No active or' potentially active faults are present at the subject site so the site is not
considered susceptible to surface rupture.
LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of this investigation we reviewed the
I publication, Landslide Hazards in the Southern Part of the San Diego Metropolitan Area" by Tan, 1995. This
reference is a comprehensive study that classifies San Diego County into areas of relative landslide susceptibility.
The subject site is located in Area 3-1. The Area 3-1 classification is assigned to areas considered generally
susceptible to slope movement. Natural slopes within the Area 3-1 classification are considered at or near their
I stability limits due to their steep inclinations and can be expected to' fail locally when adversely modified. Sites
within this classification are located outside the boundaries of known landslides.
The site was found to be underlain, below the fill layer, by Undifferentiated Santiago Peak Volcanic Rock Based
I
Ofl our experience, these materials typically have excellent strength characteristics in terms of slope stability. As
- such, it is our opinion that the potential for deep-seated Iands1iding on the subject site is low. In addition, it is our
opinion that the potential for slope failures within the existing fill slope at the western side of the subject site is
low. This is based on the proper compaction of the existing fill, the proper benching of the existing fill into
competent formational materials, and the inclination of the fill slope.
LIQUEFACTION: The near-surface soils encountered at the site are not considered susceptible to liquefaction
due to such factors as soil density, grain-size distribution and the absence of shallbw groundwater conditions.
FLOODING: Based on our review of the maps prepared by the Federal Emergency Management Agency, the
site is located outside the boundary of the 100-year and 500-year floodplains.
TSUNAMIS: Tsunamis are great sea'waves produced by submarine earthquakes or volcanic eruptions. Due to
the elevation of the site and its location, itshould not be affected by a tsunami
SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs.
Due to the site's location, it should not be affected by seiches.
CWE 2040602.1 June 29, 2004 Page No. 7
CONCLUSIONS
No geotechnical conditions were found that would preclude the construction of the proposed residential
project provided the recommendations presented in this report are followed. Based on our investigation, we
have found that. the site is underlain by artificial fills and slopewash underlain by Cretaceous-age Santiago Peak
Volcanics. The Santiago Peak Volcanics encountered in our investigation are generally medium dense to dense
and suitable to support the proposed construction. The existing artificial fill material appears to have been
properly compacted and properly benched into competent formational material and is, therefore, considered
suitable in its preseht condition to support settlement-sensitive improvements; however, the upper portions will
need to be scarified, moisture conditioned, and recompacted. The existing slopewash material is considered
unsuitable in its present condition to support settlement-sensitive improvements. As such, the slopewash
that is not removed by planned grading, will need to be removed and be replaced as properly compacted fill
material. In addition, it appears that the front residence will be traversed by a cut/fill transition. Where this
occurs, it will be necessary to undercut the cut portion of the building pad. This being accomplished, the
proposed residences can be supported by conventional spread foundations and with conventional concrete
slabs-on-grade.
No geologic hazards of sufficient magnitude to preclude development of the site as we presently contemplate
it are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable from a
geologic perspective for the proposed construction, provided the structure is. designed in accordance with the
requirements of the most recent edition of the Uniform Building Code and the local governmental agencies.
RECOMMENDATIONS
GRADING AND EARTHWORK
GENERAL All grading should conform to the guidelines presented in Appendix Chapter A33 of the
Uniform Building Code, the minimum requirements of the City of Carlsbad, and the Recommended Grading
Specifications and Special Provisions attached hereto as Appendix B, except where specifically superseded in
the text of this report. Prior to grading, a representative of Christian Wheeler Engineering should be present
at the preconstruction meeting to provide additional grading guidelines, if necessary, and to review the
earthwork schedule.
OBSERVATION OF GRADING: Continuous observation by the Geotechmcal Consultant is essential
during the grading operation to confirm conditions anticipated by our investigation, to allow adjustments in.
CWE 2040602.1 June 29, 2004 Page No.: 8
design criteria to reflect actual field conditions exposed, and to determine that the grading proceeds in general
accordance with the recommendations contained herein.
CLEARING AND GRUBBING: At the time of our site investigation, the existing building pad was cleared
of vegetation, but did support some construction debris. The site preparation should begin with the removal of
the construction debris and any vegetation and other deleterious materials from the portions of site that will be
graded and/or will receive improvements. The resulting materials should be disposed of off-site.
I SITE PREPARATION: After clearing and grubbing, the existing slopevash material should be removed
from the areas to receive fill or settlement-sensitive improvements to the contact with underlying materials of
the Santiago Peak Volcanics. Based on our limited subsurface explorations, the existing slopewash deposits are
expected to have an approximate thickness of four feet, but may be thicker in localized areas. The removals
I should extend laterally at least five feet outside the budding perimeter and at least two feet outside light exterior
improvements. No other special site preparation is considered necessary at this time.
BUILDING PAD UNDERCUTS: It appears that the front residence will be traversed by a cut/fill transition.
Where this occurs, the cut portion of the.building pad should be undercut at least three feet below finish grade.
In addition, the excavation for the partially subterranean garage may expose very dense hardrock that cannot be
excavated with light trenching equipment If this is the case, consideration should be given to undercutting the
building pad and utility alleys to at least six inches below the bottom of the foundations and utilities and
replacing the excavated. material with compacted fill material.
The bottom of all overexcavated areas should be sloped, in such a manner that water does not become trapped
in the overexcavated zone. Prior to replacing the excavated materials, the soils exposed at the bottom of the
excavation should be scarified to depth of six inches, moisture conditioned and compacted to at least 90 percent
I relative compaction.
PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements
in areas that have been cleaned out and approved to receive fill, the exposed soils should be scarified-to a depth
of 12 inches, moisture conditioned, and compacted to at least 90 percent relative compaction. No other special
ground preparation is anticipated at this time.
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COMPACTION AND METHOD OF FILLING: All structural fill placed at the site should be compacted
to a relative compaction of at least 90 percent of its maximum dry density as determined by ASTM Laboratory
Test Dl 557-91. Fills should be placed at or slightly above optimum moisture content, in lifts six to eight inches
CAE 2040602.1 June 29,2004 Page No. 9
thick-,with each lift compacted by mechanical means. Fills should consist of approved earth material, free of
trash or debris, roots, vegetation, or other materials determined to be unsuitable by our soil technicians or
project geologist. Fill material should be free of rocks or lumps of soil in excess of twelve inches in maximum
dimension. However, in the upper two feet of pad grade, no rocks or lumps of soil in excess of six inches
should be allowed.
The proposed fills should be benched at least two feet into all temporary slopes and into competent natural
or existing fill soils when the existing slope is steeper than an inclination of 5:1 (horizontal to vertical). A key
should be constructed at the toe of the proposed fill slope. The key should extend at least 12 inches into firm
natural ground and should be sloped back at least two percent into the slope area. The key should have a
minimum width of 5 feet
Utility trench backfill within five feet of the proposed structures and beneath all pavements and concrete
flatwork should be compacted to a minimum of 90 percent of its maximum dry density.
CUT AND FILL SLOPE CONSTRUCTION: Proposed cut and fill slopes will have a maximum height
of about 10 feet and are to be constructed at an inclination of 2.1 or flatter (horizontal to vertical). Care
should be taken to make sure that highly expansive materials are not placed within five feet of the face of the
fill slope. Compaction of the slope should be performed by back-rolling with a sheepsfoot compactor at
vertical intervals of four feet or less as the fill is being placed, and track-walking the face of the slope when
the slope is completed. As an alternative, the fill slopes may be overfilled by at least three feet and then cut
back to the compacted core at the design line and grade. Keys should be made at the toe of fill slopes in
accordance with the recommendations presented above under "Compaction and Method of Filling".
SURFACE DRAINAGE: Surface runoff into graded areas should be minimized. Where possible, drainage
I should be directed to suitable disposal areas via non-erodible devices such as paved swales, gunited brow
ditches, and storm drains. Pad drainage should be designed to collect and direct surface water away from
I proposed structures and the top of slopes and toward approved drainage areas. For earth areas, a minimum
gradient of one percent should be maintained.
I The ground around the proposed buildings should be graded so that surface water flows rapidly away from
the buildings without ponding. In general, we recommend that the ground adjacent to the building slopes
I away at a gradient of at least two percent. Densely vegetated areas where runoff can be impaired should have
a minimum gradient of five percent within the first five feet from the structure. Gutters and downspouts
I. should discharge to controlled drainage systems.
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CWE 2040602.1 June 29, 2004 Page No. 10
TEMPORARY CUT SLOPES: Temporary cut slopes of up to 12 feet in height are anticipated to be
required during the proposed construction. Temporary cut slopes of up to twelve feet in height, for retaining
walls, can be excavated vertical for the bottom five feet and at an inclination of 0.5 to 1.0 (horizontal to
vertical) or flatter above. All temporary cut slopes should be observed by the engineering geologist during
grading to ascertain that no unforeseen adverse conditions exist No surcharge loads such as soil or
equipment stockpiles, vehicles, etc. should be allowed within a distance from the top of temporary slopes
equal to half the slope height. Where there is not room to construct temporary slopes, temporary shoring of
the excavation sides may be necessary.
The contractor is solely responsible for designingand constructing stable, temporary excavations and may
need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the
excavation sides. The contractor's "responsible person", as defined in the OSHA Construction Standards
for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the
contractor's safety process. Temporary cut slopes should be constructed in accordance with the
recommendations presented in this section. In no other case should slope height, slope inclination, or
excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal
safety regulatiois.
SLOPE STABILITY
GENERAL All slopes at the subject site will be constructed at a slope ratio of 2:0 horizontal units to 1.0
vertical unit (2:1) or flatter, with a maximum height of about 10 feet Based on the relatively high strength
parameters of the on-site soils in their natural and compacted states, it is our opinion that the proposed slopes
will be stable in regards to deep-seated slope failure and surficial slope failure. Provided the slope is constructed
in accordance with the above recommendations, it is our opinion that the proposed slope will have a factor of
safety against failure in excess of the normally required minimum safety factor of 1.5.
EROSION CONTROL The placement of cohesionless soils at the face of slopes should be avoided. Slopes
should be planted as soon as feasible after grading. Sloughing, deep riling and slumping of surficial soils may be
anticipated if slopes are left unpianted for a long period of time, especially during the rainy season. Irrigation of
slopes should be carefully monitored to insure that only the minimum amount necessary to sustain plant life is
used. Over-irrigating could be extremely erosive and should be avoided.
F
F
CWE 2040602.1 June 29, 2004 Page No. 11
FOUNDATIONS
GENERAL: Based on our findings and engineering judgments, it is our opinion that the proposed residences
may be supported by shallow conventional continuous and isolated spread footings. The following
recommendations are considered the minimum based on soil conditions and are not intended to be lieu of
structural considerations. All foundations should be designed by a qualified structural engineer.
FOUNDATION DIMENSIONS: Spread footings supporting the proposed two- and-three-story structures
should be embedded at least 18 and 24 inches below finish pad grade, respectively. Retaining wall footings
should be embedded at least 18 inches below finish grade. Continuous should have a minimum width of 15
inches and 18 inches for two- and three-story construction, respectively. Continuous footings supporting
retaining walls and isolated footings should have a minimum width of 24 inches.
-. BEARING CAPACITY: Conventional continuous spread footings with the above minimum dimensions for
two-story structures may be designed for an allowable soil bearing pressure of 3,500 pounds per square foot.
This value may be increased by 300 and 700 psf for each addition foot of footing width and embedment,
respectively, to a maximum of 5,000 psf. This value may also be increased by one-third for combinations of
- temporary loads such as those due to wind or seismic loads.
FOOTING REINFORCEMENT: The project structural engineer should provide reinforcement
requirements for foundations. However, based on soil conditions, we recommend that the minimum
reinforcing for continuous footings consist of at least two No. 5 bars positioned three inches above the bottom
of the footing and two No. 5 bars positioned two inches below the top of the footing.
LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between the
bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coefficient
of friction between concrete and soil may be considered to be and 0.35. The passive resistance may be
considered to be equal to an equivalent fluid weight of 350 pounds per cubic foot This assumes the footings are
poured tight against undisturbed soil. If a combination of the passive pressure and friction is used, the friction
value should be reduced by one-third.
SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to be
less than about one inch and one inch in forty feet, respectively,. provided the recommendations presented in
this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and
CWE 2040602.1 June 29, 2004 Page No. 12
foundations due to shrinkage during concrete curing or redistribution of stresses, therefore some cracks
should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements.
FOUNDATION PLAN REVIEW: The foundation plans should be submitted to this office for review in
order to ascertain that the recommendations of this report have been implemented, and that no additional
recommendations are needed due to changes in the anticipated construction.
FOUNDATION EXCAVATION OBSERVATION: All foundation excavations should be observed by the
Geotechnical Consultant prior to placirig reinforcing steel or formwork to determine if the foundation
recommendations presented herein are followed. All footing excavations should be excavated neat, level, and
square. All loose or unsuitable material should be removed prior to the placement of concrete.
SEISMIC DESIGN PARAMETERS: Based on a maximum magnitude (Mmax) earthquake of 6.9 along
-, the nearest portion of the Rose Canyon Fault Zone, the Maximum Ground Acceleration at the site would be
approximately 0. 18 g. For structural design purposes, a damping ratio not greater than 5 percent of critical
- dampening, and Soil Profile Type S6 are recommended (UBC Table 16-J). Based upon the location of the
site being greater than 10 kilometers from the Rose Canyon Fault (Type B Fault), Near Source Factors Na
. equal to 1.0 and N equal to 1.0 are also applicable. These values, along with. other seismically related design
parameters from the Uniform Building Code (UBC) 1997 edition, Volume II, Chapter 16, utilizing a Seismic
Zone 4 are presented in the following table.
TABLE II: SEISMIC DESIGN PARAMETERS
UBC - Chapter 16
Table No.
Seismic
Parameter
Recommended
Value
16-I Seismic Zone Factor Z 0.40
16-J Soil Profile Type Sa
16-Q Seismic Coefficient C. 0.40 N.
16-R Seismic Coefficient C. 0.40 N
16-S Near Source Factor N. 1.0
16-T Near Source Factor N 1.0
16-U Seismic Source Type B
I
j
C\VE 2040602.1 June 29, 2004 Page No. 13
ON-GRADE SLABS
GENERAL. It is our understanding that the proposed residences will use concrete slabs-on-grade. The
following recommendations assume that the subgtade soils have been prepared in accordance with the
recommendations presented in the "Site Preparation" section of this report. In addition, the following
recommendations are considered to be the minimum slab requirements based on the soil conditions and are
not intended to be in lieu of structural considerations. All slabs should be designed by a qualified structural
engineer.
INTERIOR FLOOR SLABS: The minimum floor slab thickness should be four inches (actual) and all
floor slabs should be reinforced with at least No. 3 reinforcing bars placed at 18 inches on center each way.
Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid-height
in the floor slab. The garage slab may be constructed independent of the garage perimeter footings.
However, if the garage slab and footings are poured monolithically, the slab reinforcement should extend into
the perimeter foundations at least six inches.
MOISTURE PROTECTION FOR INTERIOR SLABS: It should be noted that it is the industry
standard that interior on-grade concrete slabs be underlain by a moisture retarder. We suggest that the
subslab moisture retarder consist of at least a two-inch-thick blanket of one-quarter-inch pea gravel or dean
coarse sand overlain by a layer of 10-mil visqueen. The visqueen should be overlain by a two-inch-thick layer
of coarse, dean sand that has less than ten percent and five percent passing the No. 100 and No. 200 sieves.
Our experience indicates that this moisture barrier should allow the transmission of from about six to twelve
pounds of moisture per 1000 square feet per day through the on-grade slab. This may be an excess amount of
moisture for some types of floor covering. If additional protection is considered necessary, the concrete mix
can be designed to help reduce the permeability of the concrete and thus moisture emission upwards through
the floor slab.
EXTERIOR CONCRETE FLATWORL Exterior slabs should have a minimum thickness of four inches.
Reinforcement and control joints should be constructed in exterior concrete flatwork to reduce the potential for
cracking and movement. Joints should be placed in exterior concrete flatwork to help control the location of
shrinkage cracks. Spacing of control joints should be in accordance with the American Concrete Institute
specifications. When patio, walks and porch slabs abut perimeter foundations they should be doweled into the
footings. •
CWE 2040602.1 June 29, 2004 Page No. 14
EARTH RETAINING WALLS
PASSIVE PRESSURE: The passive pressure for the prevailing soil conditions may be considered to be 350
pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The
coefficient of friction for concrete to soil may be assumed to be 0.35 for the resistance to lateral movement.
When combining frictional and passive resistance, the friction should be reduced by one-third. The upper 12
inches of exterior retaining wall footings should not be included in passive pressure calculations where
abutted by landscaped or unpaved areas.
EQUIVALENT FLUID PRESSURE: The active soil pressure for the design of "unrestrained" and
"restrained" earth retaining structures with level backfill may be assumed to be equivalent to the pressure of a
fluid weighing 35 and 55 pounds per cubic foot,. respectively. These values assume a diained backfill
condition.
SURCHARGE: No surcharge loads have been considered. If any surcharge loads are anticipated, this
office should be contacted for the necessary increase in lateral soil presures.
WATERPROOFING AND SUBDRAIN OBSERVATION: The project architect should provide
waterproofing details. The geotechnical engineer should be requested to verify that waterproofing has been
applied. A suggested wall subdrain detail is provided on the attached Plate Number 8. We recommend that
the Geotechnical Consultant be retained to observe all retaining wall subdrains to verify proper construction.
BACKFILL. All backfill soils should be compacted to at least 90 percent relative compaction. Expansive or
clayey soils should not be used for backfill material. The wall should not be backfllled until the masonry has
reached an adequate strength.
LIMITATIONS
REVIEW, OBSERVATION AND TESTING
The recommendations presented in this report are contingent upon our review of final plans and
specifications. Such plans-and specifications should be made available to the Geotechnical Consultant and
engineering geologist so that they may review and verify their compliance with this report and with the
Uniform Building Code.
C\VE 2040602.1 June 29, 2004 Page No. 1
It is recommended that Christian Wheeler Engineering be retained to provide continuous soil engineering
services during the earthwork operations. This is to verify compliance with the design concepts, specifications.
or recommendations and to allow design changes in the event that subsurface conditions differ from those
anticipated prior to start of construction.
UNIFORMITY OF CONDITIONS
The recommendations and opinions expressed in this report reflect our best estimate of the project
requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface
exploration locations and on the assumption that the soil conditions do not deviate appreciably from those.
encountered. It should be recognized that the performance of the foundations or temporary slopes might be
influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intennediate
and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site
development should be brought to the attention of the Geotechnical Consultant so that he may make
modifications if necessary.
This office should be advised of any changes in the project scope or proposed site grading so that we may
determine if the recommendations contained herein are appropriate. This should be verified in writing or
modified by a written addendum.
TIME LIMITATIONS
The findings of this report are valid as of this date. Changes in the condition of a property can, however,
occur with the passage of time, whether they be due to natural processes or the work of man on this or
adjacent properties. In addition, changes in the Standards-of-Practice and/or Government Codes may occur.
Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our
control Therefore, this report should not be relied upon after a period of two years without a review by us
verifying the suitability of the conclusions and recommendations.
PROFESSIONAL STANDARD
In the performance of our professional services, we comply with that level of care and skill ordinarily
I exercised by members of our profession currently practicing under similar conditions and in the same locality.
LI
CWE 2040602.1 June 29, 2004 Page No. 16
The client recognizes that subsurface conditions may vary from those encountered at the locations where our
borings, surveys, and explorations are made, and that our data, interpretations, and recommendations be
based solely on the information obtained by us. We will be responsible for those data, interpretations, and
recommendations, but shall not be responsible for the interpretations by others of the information
developed. Our services consist of professional consultation and observation only, and no warranty of any
kind whatsoever, express or implied, is made or intended in connection with the work performed or to be
performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or 'written
reports or findings.
CLIENT'S RESPONSIBILITY
It is the responsibility of the Client, or their representatives to ensure that the information and
recommendations contained herein are brought to the attention of the structural engineer and architect for
the project and incorporated into the project's plans and specifications. It is further their responsibility to take
the necessary measures to insure that the contractor and his subcontractors carry out such recommendations
during construction.
FIELD EXPLORATIONS
Six subsurface explorations were made at the locations indicated on the site plan included herewith as Plate
Number 1 on January 23, 2003, These explorations consisted of six test trenches using a Case 580L Backhoe.
The fieldwork was conducted under the observation and direction of our engineering geology personnel
The explorations were carefully logged when made. The test trench logs are presented on the following-Plate
Numbers 2 through 7. The soils are described in accordance with the Unified Soils Classification. In addition, a
I . verbal textural description, the wet color, the apparent moisture and the density or consistency are provided.
The density of granular soils is given as very loose, loose, medium dense, dense or very dense. The consistency
of silts or days is given as either very soft, soft, medium stiff, stiff; very stiff, or hard.
Disturbed "bulk" samples and relatively undisturbed "chunk" samples were taken from the trench excavations
and transported to our laboratory for testing.
~ I
1•
I.
CWE 2040602.1 June 29, 2004 Page No. 17
LABORATORY TESTING
Laboratory tests were performed in accordance. with the generally accepted American Society for Testing and
Materials (ASTM) test methods or suggested procedures. A brief description of the tests performed is
presented below.
CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The
final soil classifications are'-in accordance with the Unified Soil Classification System.
MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for
representative soil samples. This information was an aid to classification and permitted recognition of
variations in material consistency with depth. The dry unit weight is determined in pounds per cubic
foot, and the in-place moisture content is determined as a percentage of the soil's dry weight. The
results of these tests are summarized in the boring logs.
COMPACTION TEST: The maximum dry density and optimum moisture content of typical soils
were determined in the laboratory in accordance with ASTM Standard Test D-1557-91. The result of
this test is presented below.
Sample Number. Trench T-3 @ 0 - 3'
Sample Description: Light yellowish-brown, silty sand (SM)
Optimum Moisture Content 10.7%
Maximum Density. 119.0 pcf
DIRECT SHEAR TEST: A direct shear test was performed to determine the failure envelope of
the anticipated foundation soils based on yield shear strength. The shear box was designed to
accommodate a sample having a diameter of 2.375 inches or 2.50 inches and a height of 1.0 inch.
The sample was tested at different vertical loads and at a saturated moisture content. The shear stress
was applied at a constant rate of strain of approximately 0.05 inch per minute. The results of these
tests are presented below.
Sample Number. Trench T-3 ® 0-3'
Sample Type Remolded to 90 %
Angle of Internal Friction: 26
Apparent Cohesion: 300 psf
CWE 2040602.1 June 29, 2004 Page No. 18
e) GRAIN SIZE DISTRUBUTION: The grain size distribution of a selected sample was
determined in accordance with ASTM D422. The results of these tests are presented below.
Sample Location Trench T-3 ® 0-3'
Sieve Size Percent Passing -
#4 100
#8 99
#16 97
#30 95
#50 90
.#100 62.
#200 35
Soil Type SM
*
C\VE 2040602.1 June 29, 2004
REFERENCES
Appendix A, Page Al
Christian Wheeler Engineering, February 17, 2003, Report of Preliminary Geotechnical Investigation. Proposed
Residential Duplex. 2817-2819 Cazadero Drive, Carlsbad. California.
Anderson,J.G.; Rockwell, R.K. and Agnew, D.C., 1989, Past and Possible Future Earthquakes of Significance
to the San Diego Region, Earthquake Spectra, Volume 5, No. 2, 1989.
Blake, T.F., 2000, EQFAULT, A Computer Program for the Estimation of Peak Horizontal Acceleration from
3-D Fault Sources, Version 3.0, Thomas F. Blake Computer Services and Software, Thousand Oaks, California.
Boore, David M., Joyner, William B., and Furnal, ThomasE., 1997, "Empirical Near-Source Attenuation
Relationships for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Ground Velocity,
and Pseudo-Absolute Acceleration Response Spectra", in Seismological Research Letters, Volume 68, Number
1, January/February 1997.
California Division of Mines and Geology, 1998, Maps of Known Active Fault Near Source-Zones in California
and Adjacent Portions of Nevada.
Federal Emergency Management Agency, 1997, San Diego County, California and Incorporated Areas Flood
Insurance Rate Map, Panel 1051 of 2375, Map Number 060730051 F.
Hart, E.W., 1994, Fault-Rupture Hazard Zones in California, California Division of Mines andGeology Special
Publication 42.
Jennings, C.W., 1975, Fault Map of California, California Division of Mines and Geology, Map
No. 1, Scale 1:750,000.
Kern, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp:
Tan, S.S., 1995, Lendslicle Hazards in the Northern Part of the San Diego Metropolitan Area, San
Diego County, California, California Division of Mines and Geology Open-File Report 95-04.
Tan, Siang S. and Kennedy, Michael P., 1996, Geologic Maps of the Northwestern Part of San Diego County,,
California, California Division of Mines and Geology, DMG Open-File Report 96-02.
-
c\vE2o40002.i June29,2004 AppendixA, Page A2
\Vesnousky, S.G., 1986, "Earthquakes, Quaternary Faults, and Seismic Hazards in California", in
Journal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November1986.
TOPOGRAPHIC MAPS
County of San Diego, 1960, Map Sheet 342-1695; Scale: 1 inch = 200feet
County of San Diego, 1975, Map Sheet 342-1695; Scale: 1 inch 200 feet.
CWE 2040602.1 June 29, 2004 Appendix B;B-1
RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS
PROPOSED RESIDENCES
2817 AND 2819 CAZADERO tiRiVE
Lot P1 3 W1 -Tell PX4-FMW91"N HP
GENERAL INTENT
The intent of these specifications is to establish procedures for dearing, compacting natural ground,
preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the
accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/or
the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede
the provisions contained hereinafter in the case of conflict. These specifications shall only be used in
conjunction with the geotechnical report for which they are a part. No deviation from these specifications
will be allowed, except where specified in the geotechnical report or in other written communication signed
by the Geotechnical Engineer.
OBSERVATION AND TESTING
Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the
cifications. It will be necessary that the Geotechnical Engineer or his earthwork in accordance with these spe
representative provide adequate observation so that he may provide his opinion as to whether or not the
work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical
Engineer and to keep him appraised of work schedules, changes and new information and data so that he
may provide these opinions. In the event that any unusual conditions not covered by the special provisions
or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer
shall be contacted for further recommendations.
If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as
questionable or unsuitable soil; unacceptable moisture content, inadequate compaction, adverse weather, etc.,
construction should be stopped until the conditions ire remedied or corrected or he shall recommendS
rejection of this work.
Tests used to determine the degree of compaction should be performed in accordance with the following
American Society for Testing and Materials test methods:
CWE 2040602.1 June 29, 2004 Appendix B, B-2
Maximum Density & Optimum Moisture Content - ASTM D-1557-91
Density of Soil In-Place - ASTM D-1556-90 or ASTM D-2922
All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM
testing procedures.
PREPARATION OF AREAS TO RECEIVE FILL
All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of.
All areas disturbed by site grading should be left in a neat and finished appearance, free from unsightly debris.
After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6 inches,
brought to the proper moisture content, compacted and tested for the specified minimum degree of
compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is
defined as natural soil which possesses an in-situ density of at least 90. percent of its maximum dry density.
When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to I vertical unit),
the original ground shall be stepped or benched. Benches shall be cut to a firm competent formational soil.
The lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and
shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should
be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as
specified herein for dompacted natural ground. Ground slopes flatter than 20 percent shall be benched when
considered necessary by the Geotechnical Engineer.
Any abandoned buried structures encountered during grading operations must be totally removed. All
underground utilities to be abandoned beneath any proposed structure should be removed from within 10
feet of the structure and properly capped off. The resulting depressions from the above described procedure
should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer.
This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water
lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the
Geotechnical Engineer so that he may determine if any special recommendation will be necessary.
All water wells which will be abandoned should be backfllled and capped in accordance to the requirements
set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3
CWE 2040602. 1. June 29, 2004 Appendix B, -3
feet below the bottom of footing whichever is greater. The type of cap will depend on the diameter of the
well and should be determined by the Geotechnical Engineer and/or a qualified Structural Engineer.
FILL MATERIAL
Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of
vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill
the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered
in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low
strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill material, but only
with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the
Geotechnical Engineer before being brought to the site.
PLACING AND COMPACTION OF FILL
Approved fill material shall be placed in areas prepared to-receive fill in layers not to exceed 6 inches in
compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the
compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be
uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to
economically compact the layer. Compaction equipment should either be specifically designed for soil
compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either
the Special Provisions or the recommendations contained in the-preliminary geotechnical investigation
report.
When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be
carefully filled with soil such that the minimum degree of compaction recommended in the Special
Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non-
structural fills is discussed in the geotechnical report, when applicable.
Field observation and compaction tests to estimate the degree of compaction of the fill will, be taken by the
Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the
Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than
the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical
Engineer and until the desired relative compaction has been obtained.
.v
CWE 2040602.1 June 29, 2004 Appendix B, B-4
Fill slopes shall be compacted by means of sheeps foot rollers or other suitable equipment Compaction by
sheepsfoot roller shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of
two.-horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-
back to finish contours after the slope has been constructed. Slope compaction operations shall result in all
fill material six or more inches inward from the finished face of the slope having a relative compaction of at
least 90 percent of maximum dry density or the degree of compaction specified in the Special Provisions
section of this specification. The compaction operation on the slopes shall be continued until the
Geotechnical Engineer is of the opinion that the slopes will be surficially stable.
Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to
determine if the required compaction is being achieved. Where failing tests occur or other field problems
arise, the Contractor will be notified that day of such conditions by written communication from the
Geotechnical Engineer or his representative in the form of a daily field report
If the method of achieving the required slope compaction selected by the Contractor fails to produce the
necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction
is obtained, at no cost to the Owner or Gèotecbnical Engineer.
CUT SLOPES
The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material duing
the grading operations at intervals determined at his discretion. If any conditions not anticipated in the
preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse
nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions
shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating
measures are necessary.
Unless otherwise specifiedin the geotechnical report, no cut slopes shall be excavated higher or steeper than
that allowed by the ordinances of the controlling governmental agency.
ENGINEERING OBSERVATION
Field observation by the Geotechnical Engineer or his representative shall be made during the filling and
Compaction operations so that he can express his opinion regarding the conformance of the grading with
acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or
CWE 2040602.1 June 29, 2004 Appendix B, B-5
the observation and testing shall release the Grading Contractor from his duty to compact. all fill material to
the specified degree of compaction.
SEASON LIMITS
Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain,
filling operations shall not be resumed until the proper moisture content and density of the fill materials can
be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before
acceptance of work.
RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS
RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural
I ground, compacted fill, and compacted backfill shall be at least 90 percent For street and parking lot
subgrade, the upper six inches should be compacted to at least 95 percent relative compaction.
EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of
50 or greater when tested in accordance with the Uniform Building Code Standard 29-2.
OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of soil
over 6 inches in diameter. Oversized materials should not be placed in fill unless recommendations of
placement of such material is provided by the Geotechnical Engineer. At least 40 percent of the fill soils
shall pass through a No. 4 U.S. Standard Sieve.
TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building pad, the
cut portion should be undercut a minimum of one foot below the base of the proposed footings and
recompacted as structural backfill. In certain cases that would be addressed in the geotechnical report,
special footing reinforcement or a combination of special footing reinforcement and undercutting may be
required.